<!DOCTYPE HTML>
<html lang="zh-CN">


<head>
    <meta charset="utf-8">
    <meta name="keywords" content="《java并发编程的艺术》第二章总结, 戴某的博客">
    <meta name="description" content="戴某的笔记">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <meta name="renderer" content="webkit|ie-stand|ie-comp">
    <meta name="mobile-web-app-capable" content="yes">
    <meta name="format-detection" content="telephone=no">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
    <!-- Global site tag (gtag.js) - Google Analytics -->


    <title>《java并发编程的艺术》第二章总结 | 戴某的博客</title>
    <link rel="icon" type="image/png" href="/dai_modest/favicon.png">

    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/awesome/css/all.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/materialize/materialize.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/aos/aos.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/animate/animate.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/lightGallery/css/lightgallery.min.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/css/matery.css">
    <link rel="stylesheet" type="text/css" href="/dai_modest/css/my.css">

    <script src="/dai_modest/libs/jquery/jquery.min.js"></script>

<meta name="generator" content="Hexo 5.4.0"><link rel="alternate" href="/dai_modest/atom.xml" title="戴某的博客" type="application/atom+xml">
<link rel="stylesheet" href="/dai_modest/css/prism-tomorrow.css" type="text/css"></head>



   <style>
    body{
       background-image: url(https://cdn.jsdelivr.net/gh/Tokisaki-Galaxy/res/site/medias/background.jpg);
       background-repeat:no-repeat;
       background-size:cover;
       background-attachment:fixed;
    }
</style>



<body>
    <header class="navbar-fixed">
    <nav id="headNav" class="bg-color nav-transparent">
        <div id="navContainer" class="nav-wrapper container">
            <div class="brand-logo">
                <a href="/dai_modest/" class="waves-effect waves-light">
                    
                    <img src="/dai_modest/medias/logo.png" class="logo-img" alt="LOGO">
                    
                    <span class="logo-span">戴某的博客</span>
                </a>
            </div>
            

<a href="#" data-target="mobile-nav" class="sidenav-trigger button-collapse"><i class="fas fa-bars"></i></a>
<ul class="right nav-menu">
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/" class="waves-effect waves-light">
      
      <i class="fas fa-home" style="zoom: 0.6;"></i>
      
      <span>首页</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/tags" class="waves-effect waves-light">
      
      <i class="fas fa-tags" style="zoom: 0.6;"></i>
      
      <span>标签</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/categories" class="waves-effect waves-light">
      
      <i class="fas fa-bookmark" style="zoom: 0.6;"></i>
      
      <span>分类</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/archives" class="waves-effect waves-light">
      
      <i class="fas fa-archive" style="zoom: 0.6;"></i>
      
      <span>归档</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/about" class="waves-effect waves-light">
      
      <i class="fas fa-user-circle" style="zoom: 0.6;"></i>
      
      <span>关于</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/contact" class="waves-effect waves-light">
      
      <i class="fas fa-comments" style="zoom: 0.6;"></i>
      
      <span>留言板</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/dai_modest/friends" class="waves-effect waves-light">
      
      <i class="fas fa-address-book" style="zoom: 0.6;"></i>
      
      <span>友情链接</span>
    </a>
    
  </li>
  
  <li>
    <a href="#searchModal" class="modal-trigger waves-effect waves-light">
      <i id="searchIcon" class="fas fa-search" title="搜索" style="zoom: 0.85;"></i>
    </a>
  </li>
</ul>


<div id="mobile-nav" class="side-nav sidenav">

    <div class="mobile-head bg-color">
        
        <img src="/dai_modest/medias/logo.png" class="logo-img circle responsive-img">
        
        <div class="logo-name">戴某的博客</div>
        <div class="logo-desc">
            
            戴某的笔记
            
        </div>
    </div>

    

    <ul class="menu-list mobile-menu-list">
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-home"></i>
			
			首页
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/tags" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-tags"></i>
			
			标签
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/categories" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-bookmark"></i>
			
			分类
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/archives" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-archive"></i>
			
			归档
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/about" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-user-circle"></i>
			
			关于
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/contact" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-comments"></i>
			
			留言板
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/dai_modest/friends" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-address-book"></i>
			
			友情链接
		</a>
          
        </li>
        
        
        <li><div class="divider"></div></li>
        <li>
            <a href="https://github.com/blinkfox/hexo-theme-matery" class="waves-effect waves-light" target="_blank">
                <i class="fab fa-github-square fa-fw"></i>Fork Me
            </a>
        </li>
        
    </ul>
</div>


        </div>

        
            <style>
    .nav-transparent .github-corner {
        display: none !important;
    }

    .github-corner {
        position: absolute;
        z-index: 10;
        top: 0;
        right: 0;
        border: 0;
        transform: scale(1.1);
    }

    .github-corner svg {
        color: #0f9d58;
        fill: #fff;
        height: 64px;
        width: 64px;
    }

    .github-corner:hover .octo-arm {
        animation: a 0.56s ease-in-out;
    }

    .github-corner .octo-arm {
        animation: none;
    }

    @keyframes a {
        0%,
        to {
            transform: rotate(0);
        }
        20%,
        60% {
            transform: rotate(-25deg);
        }
        40%,
        80% {
            transform: rotate(10deg);
        }
    }
</style>

<a href="https://github.com/blinkfox/hexo-theme-matery" class="github-corner tooltipped hide-on-med-and-down" target="_blank"
   data-tooltip="Fork Me" data-position="left" data-delay="50">
    <svg viewBox="0 0 250 250" aria-hidden="true">
        <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
        <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
              fill="currentColor" style="transform-origin: 130px 106px;" class="octo-arm"></path>
        <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z"
              fill="currentColor" class="octo-body"></path>
    </svg>
</a>
        
    </nav>

</header>

    



<div class="bg-cover pd-header post-cover" style="background-image: url('/dai_modest/medias/featureimages/14.jpg')">
    <div class="container" style="right: 0px;left: 0px;">
        <div class="row">
            <div class="col s12 m12 l12">
                <div class="brand">
                    <h1 class="description center-align post-title">《java并发编程的艺术》第二章总结</h1>
                </div>
            </div>
        </div>
    </div>
</div>




<main class="post-container content">

    
    <link rel="stylesheet" href="/dai_modest/libs/tocbot/tocbot.css">
<style>
    #articleContent h1::before,
    #articleContent h2::before,
    #articleContent h3::before,
    #articleContent h4::before,
    #articleContent h5::before,
    #articleContent h6::before {
        display: block;
        content: " ";
        height: 100px;
        margin-top: -100px;
        visibility: hidden;
    }

    #articleContent :focus {
        outline: none;
    }

    .toc-fixed {
        position: fixed;
        top: 64px;
    }

    .toc-widget {
        width: 345px;
        padding-left: 20px;
    }

    .toc-widget .toc-title {
        padding: 35px 0 15px 17px;
        font-size: 1.5rem;
        font-weight: bold;
        line-height: 1.5rem;
    }

    .toc-widget ol {
        padding: 0;
        list-style: none;
    }

    #toc-content {
        padding-bottom: 30px;
        overflow: auto;
    }

    #toc-content ol {
        padding-left: 10px;
    }

    #toc-content ol li {
        padding-left: 10px;
    }

    #toc-content .toc-link:hover {
        color: #42b983;
        font-weight: 700;
        text-decoration: underline;
    }

    #toc-content .toc-link::before {
        background-color: transparent;
        max-height: 25px;

        position: absolute;
        right: 23.5vw;
        display: block;
    }

    #toc-content .is-active-link {
        color: #42b983;
    }

    #floating-toc-btn {
        position: fixed;
        right: 15px;
        bottom: 76px;
        padding-top: 15px;
        margin-bottom: 0;
        z-index: 998;
    }

    #floating-toc-btn .btn-floating {
        width: 48px;
        height: 48px;
    }

    #floating-toc-btn .btn-floating i {
        line-height: 48px;
        font-size: 1.4rem;
    }
</style>
<div class="row">
    <div id="main-content" class="col s12 m12 l9">
        <!-- 文章内容详情 -->
<div id="artDetail">
    <div class="card">
        <div class="card-content article-info">
            <div class="row tag-cate">
                <div class="col s7">
                    
                    <div class="article-tag">
                        
                            <a href="/dai_modest/tags/java/">
                                <span class="chip bg-color">java</span>
                            </a>
                        
                    </div>
                    
                </div>
                <div class="col s5 right-align">
                    
                    <div class="post-cate">
                        <i class="fas fa-bookmark fa-fw icon-category"></i>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/" class="post-category">
                                书籍
                            </a>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                笔记类
                            </a>
                        
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/%E3%80%8Ajava%E5%B9%B6%E5%8F%91%E7%BC%96%E7%A8%8B%E7%9A%84%E8%89%BA%E6%9C%AF%E3%80%8B/" class="post-category">
                                《java并发编程的艺术》
                            </a>
                        
                    </div>
                    
                </div>
            </div>

            <div class="post-info">
                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-minus fa-fw"></i>发布日期:&nbsp;&nbsp;
                    2022-03-22
                </div>
                

                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-check fa-fw"></i>更新日期:&nbsp;&nbsp;
                    2022-03-25
                </div>
                

                
                <div class="info-break-policy">
                    <i class="far fa-file-word fa-fw"></i>文章字数:&nbsp;&nbsp;
                    3.3k
                </div>
                

                

                
            </div>
        </div>
        <hr class="clearfix">

        
        <!-- 是否加载使用自带的 prismjs. -->
        <link rel="stylesheet" href="/dai_modest/libs/prism/prism.css">
        

        
        <!-- 代码块折行 -->
        <style type="text/css">
            code[class*="language-"], pre[class*="language-"] { white-space: pre-wrap !important; }
        </style>
        

        <div class="card-content article-card-content">
            <div id="articleContent">
                <h1 id="java并发机制的底层实现原理"><a href="#java并发机制的底层实现原理" class="headerlink" title="java并发机制的底层实现原理"></a>java并发机制的底层实现原理</h1><p>java中所使用的并发机制依赖于JVM的实现和CPU的指令。因为：java代码在编译后会变成java字节码，字节码被类加载器加载到JVM里，JVM执行字节码，最终需要转化成汇编指令在CPU上执行。</p>
<h2 id="常用CPU术语定义"><a href="#常用CPU术语定义" class="headerlink" title="常用CPU术语定义"></a>常用CPU术语定义</h2><p>内存屏障：一组处理器指令，用于对现实对内存操作的限制。</p>
<p>缓存行：CPU高速缓存中可以分配的最小存储单位。</p>
<p>原子操作：不可中断的一个或一系列操作。</p>
<p>缓存行填充：当处理器识别到从内存中读取操作是可缓存的，那么处理器会读取整个高速缓存行（多核处理器就是多个）到适当的缓存中。</p>
<p>缓存命中：如果进行高速缓存行填充操作的内存位置仍是下次处理器访问的地址，处理器从缓存中读取操作数，而不是从内存读取。</p>
<p>写命中：当处理器将操作数写回到一个内存缓存的区域时，它首先会检查这个缓存的内存地址是否在缓存行中，如果是一个有效的缓存行，则处理器将这个操作数写回到缓存而不是写回到内存，这个操作被称为写命中。</p>
<p>写缺失：一个有效的缓存行被写入到不存在的内存区域。</p>
<h2 id="volatile的应用"><a href="#volatile的应用" class="headerlink" title="volatile的应用"></a>volatile的应用</h2><p>volatile是轻量级的synchronized。它在多处理器开发中保证了共享变量的“可见性”。</p>
<p>java语言规范第3版中对volatile的定义如下：<strong>java编程语言允许线程访问共享变量，为了确保共享变量能被准确和一致地更新，线程应该确保通过排他锁单独获得这个变量。</strong></p>
<p>底层：在使用volatile变量修饰的共享变量在进行写操作的时候会多出一个带<strong>lock</strong>前缀的指令。</p>
<p>而这个lock前缀在多核处理器下会引发两件事情：</p>
<p>1.将当期处理器缓存行的数据写回到写系统内存。</p>
<p>2.这个写回内存的操作会使其他CPU里缓存了该内存地址的数据无效。</p>
<p>（LOCK信号一般是锁缓存不锁总线，锁总线开销比较大）</p>
<p>1.为了提高处理速度，处理器不直接和内存进行通信，而是先将系统内存的数据读取到内部缓存后进行操作，但操作完不知道何时会写到内存。2.如果对声明volatile的变量进行写操作，JVM就会向处理器发送一条lock前缀的指令，将这个变量所在缓存行的数据写回到系统内存，</p>
<p>缓存一致性： 在多个处理器下，为了保证各个处理器的缓存是一致的，就会实现缓存一致性协议，1.每个处理器通过<strong>嗅探</strong>在总线上传播的数据来检查自己缓存是不是过期了。2.如果发现缓存行对应的内存地址被修改。3.就会将当前处理器的缓存行设置为无效状态。4.当处理器对这个数据进行操作的时候会重新从系统内存中把数据读到处理器缓存里。</p>
<p>volatile优化：追加字节优化性能（追加64字节能够提高并发编程的效率）。因为如果队列的头节点和尾节点都不足64字节那么就会有一种可能是头节点和尾节点加载到同一个缓存行中，是头、尾节点在修改时不会相互锁定。</p>
<p>但是并不是所有的都可以使用追加64字节进行优化：<strong>缓存行不是64字宽的处理器</strong>，<strong>共享变量不会被频繁地被写</strong>。</p>
<h2 id="synchronized的实现原理与应用"><a href="#synchronized的实现原理与应用" class="headerlink" title="synchronized的实现原理与应用"></a>synchronized的实现原理与应用</h2><p>synchronized通常被称作重量级锁，<strong>javase1.6</strong>中为了减少获得锁和释放锁带来的性能消耗引入的偏向锁和轻量级锁、以及锁的存储结构和升级过程。</p>
<p>java中的每一个对象都可以作为锁。</p>
<p>对于普通同步方法，锁是当前对象的实例。</p>
<p>对于静态同步方法，锁是当前类的class对象。</p>
<p>对于同步方法块，锁是synchronized括号里配置的对象。</p>
<p>底层实现：在JVM中代码块同步使用的是monitor对象实现同步。当且一个monitor被持有后，它将处于锁定状态。线程执行到monitorenter指令时，将会尝试获取对象锁对应的monitor的所有权，且尝试获得对象的锁。</p>
<h3 id="java对象头"><a href="#java对象头" class="headerlink" title="java对象头"></a>java对象头</h3><p>java对象头由2~3个部分组成：</p>
<p>1.Mark Word（存储对象的hashCode或锁信息）</p>
<p>2.存储到对象类型数据的指针</p>
<p>3.数组的长度（如果是数组才会有）</p>
<p>Mark Word里默认存储对象的HashCode、分代年龄和锁标志位（4个状态2bit）。</p>
<h3 id="锁的升级与对比"><a href="#锁的升级与对比" class="headerlink" title="锁的升级与对比"></a>锁的升级与对比</h3><p>javase 1.6后引入了偏向锁和轻量级锁。锁的状态从低到高依次是：无锁状态、偏向锁状态、轻量级锁和重量级锁。（锁可以升级但不能降级）</p>
<p><strong>偏向锁加锁</strong>：当一个线程访问同步块并获取锁时，会在<strong>对象头和栈帧中的锁记录</strong>里存储锁偏向的线程ID，以后该线程在进入和退出同步代码块时不需要进行CAS操作来加锁和解锁。</p>
<p><strong>偏向锁的解锁</strong>：偏向锁使用了一种等到<strong>竞争出现才会释放</strong>的机制。所以当其他线程尝试竞争偏向锁时，持有偏向锁的线程才会释放锁（偏向锁的撤销，需要等待全局安全点，在这个时间点上没有其他正在执行的字节码）。</p>
<p><strong>偏向锁解锁过程</strong>：它首先会暂停拥有偏向锁的线程，然后<strong>检查线程是否存活</strong>，如果不处于活动状态就将对象头设置成无锁状态。如果线程处于活动状态，拥有偏向锁的栈就会被执行，遍历偏向对象的锁记录，最后的结果就是：对象头和栈中锁记录中的<strong>Mark Word要么重新偏向于其他线程</strong>，要么<strong>恢复到无锁</strong>或者标记对象<strong>不适合作为偏向锁</strong>，最后唤醒暂停的线程。</p>
<p><strong>轻量级加锁</strong>：线程在执行同步块之前，JVM会先在当前线程的栈帧中<strong>创建用于存储锁记录的空间</strong>，并将对象头和Mark Word<strong>复制到锁记录</strong>中，官方称为<strong>Dispalace Mark Word</strong>。然后线程尝试使用CAS操作将对象头中的Mark Word替换为指向锁记录的指针。如果成功，那么当前线程就会获得轻量级锁，如果失败就会表示有其他线程竞争锁，当前线程便尝试使用自旋来获取锁。</p>
<p><strong>轻量级解锁</strong>：轻量级解锁时，会使用原子的CAS操作将Displace Mark Word替换回到对象头。如果成功则表示竞争没有发生。如果失败表示当前锁存在竞争，锁就会膨胀成重量级锁。</p>
<p>为了避免无用的自旋，一旦锁升级成重量级锁，就不会再恢复到轻量级锁状态。其他线程试图获取锁时，都会被阻塞住，当持有锁的线程释放之后会唤醒这些线程，唤醒的线程就会进行新一轮的夺锁之争。</p>
<h3 id="锁的优缺点对比"><a href="#锁的优缺点对比" class="headerlink" title="锁的优缺点对比"></a>锁的优缺点对比</h3><p><strong>偏向锁</strong></p>
<p>优点：加锁和解锁不需要额外的消耗。</p>
<p>缺点：如果线程间存在锁竞争，会带来额外的锁的撤销。</p>
<p>适用场景：适用于只有一个线程访问同步代码块的场景。</p>
<p><strong>轻量级锁</strong></p>
<p>优点：竞争的线程不会被阻塞，提高了程序的相应速度。</p>
<p>缺点：如果始终得不到锁竞争的线程，使用自旋会消耗CPU。</p>
<p>适用场景：追求相应时间，同步块执行速度非常快（少量线程）。</p>
<p><strong>重量级锁</strong></p>
<p>优点：线程竞争不使用自旋，不会消耗CPU。</p>
<p>缺点：线程阻塞，响应时间缓慢。</p>
<p>适用场景：追求吞吐量，同步代码块执行时间较长。（大量线程）</p>
<h2 id="原子操作的实现原理"><a href="#原子操作的实现原理" class="headerlink" title="原子操作的实现原理"></a>原子操作的实现原理</h2><p>定义：原子的本意是“不能被进一步分割的最小粒子”，原子操作意为“不可被中断的一个或一系列操作”。</p>
<p>常见术语：</p>
<p>CPU流水线：在CPU中由5<del>6个不同功能的电路单元组成<strong>一条指令</strong>处理流水线，然后将一条X86指令分成5</del>6步后再由这些电路单元<strong>分别执行</strong>，这样就能实现在一个CPU时钟周期完成一条指令，因此提高CPU的运算速度。</p>
<p>内存顺序冲突：内存顺序冲突一般是由假共享引起的，假共享是指多个CPU同时修改同一个缓存行的不同部分而引起其中一个CPU的操作无效，当出现内存顺序冲突时，CPU必须清空流水线。</p>
<h3 id="处理器是如何实现原子操作"><a href="#处理器是如何实现原子操作" class="headerlink" title="处理器是如何实现原子操作"></a>处理器是如何实现原子操作</h3><p>处理器提供<strong>总线锁定</strong>和<strong>缓存锁定</strong>两个机制来保证复杂内存操作的原子性。</p>
<p><strong>总线锁定</strong>：使用处理器时提供一个LOCK#信号，当一个处理器在总线上输出此信号时，其他处理器的请求将被阻塞住，那么这个处理器可以独占共享内存。</p>
<p><strong>缓存锁定</strong>：内存区域如果被缓存在处理器缓存行中，并且在lock操作期间被锁定，那么当它执行锁操作回写到内存时，处理器不在总线上声言LCOK#信号，而是修改内部内存地址，并允许它的缓存一致性机制来保证操作的原子性。（意思是，我们只需要保证多个处理器中其中一个处理器缓存是修改了的，其他处理器根据缓存一致性原则而将其他缓存一起修改）</p>
<p>因为<strong>总线锁定</strong>会导致其他变量一样被锁定无法操作，所以<strong>效率十分低下</strong>，使用<strong>缓存锁定</strong>就避免了总线锁定而是精确到对应的共享变量<strong>效率更高</strong>。</p>
<p>不能使用缓存锁定的情况：</p>
<p>1.当操作数据不能被缓存在处理器内部，或操作的数据跨<strong>多个缓存行</strong>，处理器会调用总线锁定。</p>
<p>2.部分处理器不支持缓存处理。</p>
<h3 id="java是如何实现原子操作的"><a href="#java是如何实现原子操作的" class="headerlink" title="java是如何实现原子操作的"></a>java是如何实现原子操作的</h3><p>java中可以通过<strong>锁</strong>和<strong>循环CAS操作</strong>的方式来实现原子操作。</p>
<p>JDK的并发包中提供了部分CAS操作的工具类AtomicInteger，AtomicLong，AtomicBoolean。这些保证包含一个函数<strong>compareAndSet</strong>(旧值，修改后的值);</p>
<p><strong>循环CAS操作</strong></p>
<p>CAS实现原子操作的三大问题：<strong>ABA问题</strong>，<strong>循环时间长开销大</strong>，<strong>只能保证一个共享变量的原子操作</strong>。</p>
<p><strong>ABA问题</strong>：因为CAS操作的时候检查值有没有发生改变，但是如果一个值原来为A但是操作后变成B后来又变成了A那么它的值没有发生改变，但是实际上却发生改变了。解决方法：我们需要在每次操作的时候加上版本号比如所1A-&gt;2B-&gt;3A，检查的时候首先检查当前引用是否等于预期引用，并检查当前标志是否等于预期标志。</p>
<p><strong>循环时间长开销大</strong>：自旋CAS操作如果长时间不成功，会给CPU带来非常大的执行开销。JVM如果支持<strong>处理器提供的pause</strong>，那么小了会有一定的提升。<strong>pause指令</strong>的两个作用：1.<strong>延迟流水线执行指令</strong>，使CPU不会消耗过多的执行资源。2.它可以避免在退出循环的时候因<strong>内存顺序冲突</strong>而引起流水线被清空的情况。</p>
<p><strong>只能保证一个共享变量的原子操作</strong>：对一个共享变量执行原子操作，CAS可以保障。但是对于多个共享变量的操作的时候循环CAS操作就不能保障原子性，如果我们将多个共享变量合并成一个共享变量（对象）来操作，来保证对象之间的原子性。</p>
<p><strong>锁机制实现原子操作</strong></p>
<p>锁机制保证了只有获得锁的线程才能操作锁定的内存区域，JVM内部实现了很多锁的机制，偏向锁，轻量级锁和互斥锁（synchronized）。</p>
<p>除了偏向锁，JVM的其他实现锁的方式都用了<strong>循环CAS方式来获取锁</strong>，当它退出同步的时候都使用了<strong>循环CAS释放锁</strong>。</p>

                
            </div>
            <hr/>

            

    <div class="reprint" id="reprint-statement">
        
            <div class="reprint__author">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-user">
                        文章作者:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="/dai_modest/about" rel="external nofollow noreferrer">戴某人</a>
                </span>
            </div>
            <div class="reprint__type">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-link">
                        文章链接:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="https://modest2001.gitee.io/dai_modest/dai_modest/2022/03/22/java-bing-fa-bian-cheng-de-yi-zhu-di-er-zhang-zong-jie/">https://modest2001.gitee.io/dai_modest/dai_modest/2022/03/22/java-bing-fa-bian-cheng-de-yi-zhu-di-er-zhang-zong-jie/</a>
                </span>
            </div>
            <div class="reprint__notice">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-copyright">
                        版权声明:
                    </i>
                </span>
                <span class="reprint-info">
                    本博客所有文章除特別声明外，均采用
                    <a href="https://creativecommons.org/licenses/by/4.0/deed.zh" rel="external nofollow noreferrer" target="_blank">CC BY 4.0</a>
                    许可协议。转载请注明来源
                    <a href="/dai_modest/about" target="_blank">戴某人</a>
                    !
                </span>
            </div>
        
    </div>

    <script async defer>
      document.addEventListener("copy", function (e) {
        let toastHTML = '<span>复制成功，请遵循本文的转载规则</span><button class="btn-flat toast-action" onclick="navToReprintStatement()" style="font-size: smaller">查看</a>';
        M.toast({html: toastHTML})
      });

      function navToReprintStatement() {
        $("html, body").animate({scrollTop: $("#reprint-statement").offset().top - 80}, 800);
      }
    </script>



            <div class="tag_share" style="display: block;">
                <div class="post-meta__tag-list" style="display: inline-block;">
                    
                        <div class="article-tag">
                            
                                <a href="/dai_modest/tags/java/">
                                    <span class="chip bg-color">java</span>
                                </a>
                            
                        </div>
                    
                </div>
                <div class="post_share" style="zoom: 80%; width: fit-content; display: inline-block; float: right; margin: -0.15rem 0;">
                    <link rel="stylesheet" type="text/css" href="/dai_modest/libs/share/css/share.min.css">
<div id="article-share">

    
    <div class="social-share" data-sites="twitter,facebook,google,qq,qzone,wechat,weibo,douban,linkedin" data-wechat-qrcode-helper="<p>微信扫一扫即可分享！</p>"></div>
    <script src="/dai_modest/libs/share/js/social-share.min.js"></script>
    

    
    <script type="text/javascript" src="//s7.addthis.com/js/300/addthis_widget.js#pubid="></script>
    <div class="addthis_inline_share_toolbox"></div>
    

</div>

                </div>
            </div>
            
                <style>
    #reward {
        margin: 40px 0;
        text-align: center;
    }

    #reward .reward-link {
        font-size: 1.4rem;
        line-height: 38px;
    }

    #reward .btn-floating:hover {
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.2), 0 5px 15px rgba(0, 0, 0, 0.2);
    }

    #rewardModal {
        width: 320px;
        height: 350px;
    }

    #rewardModal .reward-title {
        margin: 15px auto;
        padding-bottom: 5px;
    }

    #rewardModal .modal-content {
        padding: 10px;
    }

    #rewardModal .close {
        position: absolute;
        right: 15px;
        top: 15px;
        color: rgba(0, 0, 0, 0.5);
        font-size: 1.3rem;
        line-height: 20px;
        cursor: pointer;
    }

    #rewardModal .close:hover {
        color: #ef5350;
        transform: scale(1.3);
        -moz-transform:scale(1.3);
        -webkit-transform:scale(1.3);
        -o-transform:scale(1.3);
    }

    #rewardModal .reward-tabs {
        margin: 0 auto;
        width: 210px;
    }

    .reward-tabs .tabs {
        height: 38px;
        margin: 10px auto;
        padding-left: 0;
    }

    .reward-content ul {
        padding-left: 0 !important;
    }

    .reward-tabs .tabs .tab {
        height: 38px;
        line-height: 38px;
    }

    .reward-tabs .tab a {
        color: #fff;
        background-color: #ccc;
    }

    .reward-tabs .tab a:hover {
        background-color: #ccc;
        color: #fff;
    }

    .reward-tabs .wechat-tab .active {
        color: #fff !important;
        background-color: #22AB38 !important;
    }

    .reward-tabs .alipay-tab .active {
        color: #fff !important;
        background-color: #019FE8 !important;
    }

    .reward-tabs .reward-img {
        width: 210px;
        height: 210px;
    }
</style>

<div id="reward">
    <a href="#rewardModal" class="reward-link modal-trigger btn-floating btn-medium waves-effect waves-light red">赏</a>

    <!-- Modal Structure -->
    <div id="rewardModal" class="modal">
        <div class="modal-content">
            <a class="close modal-close"><i class="fas fa-times"></i></a>
            <h4 class="reward-title">你的赏识是我前进的动力</h4>
            <div class="reward-content">
                <div class="reward-tabs">
                    <ul class="tabs row">
                        <li class="tab col s6 alipay-tab waves-effect waves-light"><a href="#alipay">支付宝</a></li>
                        <li class="tab col s6 wechat-tab waves-effect waves-light"><a href="#wechat">微 信</a></li>
                    </ul>
                    <div id="alipay">
                        <img src="/dai_modest/medias/reward/alipay.jpg" class="reward-img" alt="支付宝打赏二维码">
                    </div>
                    <div id="wechat">
                        <img src="/dai_modest/medias/reward/wechat.png" class="reward-img" alt="微信打赏二维码">
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

<script>
    $(function () {
        $('.tabs').tabs();
    });
</script>

            
        </div>
    </div>

    

    

    

    

    

    

    

    

    

<article id="prenext-posts" class="prev-next articles">
    <div class="row article-row">
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge left-badge text-color">
                <i class="fas fa-chevron-left"></i>&nbsp;上一篇</div>
            <div class="card">
                <a href="/dai_modest/2022/03/26/rabbitmq-xue-xi-bi-ji-01/">
                    <div class="card-image">
                        
                        
                        <img src="/dai_modest/medias/featureimages/19.jpg" class="responsive-img" alt="RabbitMQ学习笔记01">
                        
                        <span class="card-title">RabbitMQ学习笔记01</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            消息队列的概念和安装
                        
                    </div>
                    <div class="publish-info">
                        <span class="publish-date">
                            <i class="far fa-clock fa-fw icon-date"></i>2022-03-26
                        </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/dai_modest/categories/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                    笔记类
                                </a>
                            
                            <a href="/dai_modest/categories/%E7%AC%94%E8%AE%B0%E7%B1%BB/%E6%B6%88%E6%81%AF%E4%B8%AD%E9%97%B4%E4%BB%B6/" class="post-category">
                                    消息中间件
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/dai_modest/tags/RabbitMQ/">
                        <span class="chip bg-color">RabbitMQ</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge right-badge text-color">
                下一篇&nbsp;<i class="fas fa-chevron-right"></i>
            </div>
            <div class="card">
                <a href="/dai_modest/2022/03/22/java-bing-fa-bian-cheng-de-yi-zhu-di-yi-zhang-zong-jie/">
                    <div class="card-image">
                        
                        
                        <img src="/dai_modest/medias/featureimages/10.jpg" class="responsive-img" alt="《java并发编程的艺术》第一章总结">
                        
                        <span class="card-title">《java并发编程的艺术》第一章总结</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            并发编程的挑战
                        
                    </div>
                    <div class="publish-info">
                            <span class="publish-date">
                                <i class="far fa-clock fa-fw icon-date"></i>2022-03-22
                            </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/" class="post-category">
                                    书籍
                                </a>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/" class="post-category">
                                    笔记类
                                </a>
                            
                            <a href="/dai_modest/categories/%E4%B9%A6%E7%B1%8D/%E7%AC%94%E8%AE%B0%E7%B1%BB/%E3%80%8Ajava%E5%B9%B6%E5%8F%91%E7%BC%96%E7%A8%8B%E7%9A%84%E8%89%BA%E6%9C%AF%E3%80%8B/" class="post-category">
                                    《java并发编程的艺术》
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/dai_modest/tags/java/">
                        <span class="chip bg-color">java</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
    </div>
</article>

</div>


<script>
    $('#articleContent').on('copy', function (e) {
        // IE8 or earlier browser is 'undefined'
        if (typeof window.getSelection === 'undefined') return;

        var selection = window.getSelection();
        // if the selection is short let's not annoy our users.
        if (('' + selection).length < Number.parseInt('120')) {
            return;
        }

        // create a div outside of the visible area and fill it with the selected text.
        var bodyElement = document.getElementsByTagName('body')[0];
        var newdiv = document.createElement('div');
        newdiv.style.position = 'absolute';
        newdiv.style.left = '-99999px';
        bodyElement.appendChild(newdiv);
        newdiv.appendChild(selection.getRangeAt(0).cloneContents());

        // we need a <pre> tag workaround.
        // otherwise the text inside "pre" loses all the line breaks!
        if (selection.getRangeAt(0).commonAncestorContainer.nodeName === 'PRE' || selection.getRangeAt(0).commonAncestorContainer.nodeName === 'CODE') {
            newdiv.innerHTML = "<pre>" + newdiv.innerHTML + "</pre>";
        }

        var url = document.location.href;
        newdiv.innerHTML += '<br />'
            + '来源: 戴某的博客<br />'
            + '文章作者: 戴某人<br />'
            + '文章链接: <a href="' + url + '">' + url + '</a><br />'
            + '本文章著作权归作者：戴某人所有，任何形式的转载都请注明出处。';

        selection.selectAllChildren(newdiv);
        window.setTimeout(function () {bodyElement.removeChild(newdiv);}, 200);
    });
</script>


<!-- 代码块功能依赖 -->
<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeBlockFuction.js"></script>

<!-- 代码语言 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeLang.js"></script>


<!-- 代码块复制 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeCopy.js"></script>


<!-- 代码块收缩 -->

<script type="text/javascript" src="/dai_modest/libs/codeBlock/codeShrink.js"></script>


    </div>
    <div id="toc-aside" class="expanded col l3 hide-on-med-and-down">
        <div class="toc-widget card" style="background-color: white;">
            <div class="toc-title"><i class="far fa-list-alt"></i>&nbsp;&nbsp;目录</div>
            <div id="toc-content"></div>
        </div>
    </div>
</div>

<!-- TOC 悬浮按钮. -->

<div id="floating-toc-btn" class="hide-on-med-and-down">
    <a class="btn-floating btn-large bg-color">
        <i class="fas fa-list-ul"></i>
    </a>
</div>


<script src="/dai_modest/libs/tocbot/tocbot.min.js"></script>
<script>
    $(function () {
        tocbot.init({
            tocSelector: '#toc-content',
            contentSelector: '#articleContent',
            headingsOffset: -($(window).height() * 0.4 - 45),
            collapseDepth: Number('0'),
            headingSelector: 'h2, h3, h4'
        });

        // modify the toc link href to support Chinese.
        let i = 0;
        let tocHeading = 'toc-heading-';
        $('#toc-content a').each(function () {
            $(this).attr('href', '#' + tocHeading + (++i));
        });

        // modify the heading title id to support Chinese.
        i = 0;
        $('#articleContent').children('h2, h3, h4').each(function () {
            $(this).attr('id', tocHeading + (++i));
        });

        // Set scroll toc fixed.
        let tocHeight = parseInt($(window).height() * 0.4 - 64);
        let $tocWidget = $('.toc-widget');
        $(window).scroll(function () {
            let scroll = $(window).scrollTop();
            /* add post toc fixed. */
            if (scroll > tocHeight) {
                $tocWidget.addClass('toc-fixed');
            } else {
                $tocWidget.removeClass('toc-fixed');
            }
        });

        
        /* 修复文章卡片 div 的宽度. */
        let fixPostCardWidth = function (srcId, targetId) {
            let srcDiv = $('#' + srcId);
            if (srcDiv.length === 0) {
                return;
            }

            let w = srcDiv.width();
            if (w >= 450) {
                w = w + 21;
            } else if (w >= 350 && w < 450) {
                w = w + 18;
            } else if (w >= 300 && w < 350) {
                w = w + 16;
            } else {
                w = w + 14;
            }
            $('#' + targetId).width(w);
        };

        // 切换TOC目录展开收缩的相关操作.
        const expandedClass = 'expanded';
        let $tocAside = $('#toc-aside');
        let $mainContent = $('#main-content');
        $('#floating-toc-btn .btn-floating').click(function () {
            if ($tocAside.hasClass(expandedClass)) {
                $tocAside.removeClass(expandedClass).hide();
                $mainContent.removeClass('l9');
            } else {
                $tocAside.addClass(expandedClass).show();
                $mainContent.addClass('l9');
            }
            fixPostCardWidth('artDetail', 'prenext-posts');
        });
        
    });
</script>

    

</main>




    <footer class="page-footer bg-color">
    
        <link rel="stylesheet" href="/dai_modest/libs/aplayer/APlayer.min.css">
<style>
    .aplayer .aplayer-lrc p {
        
        display: none;
        
        font-size: 12px;
        font-weight: 700;
        line-height: 16px !important;
    }

    .aplayer .aplayer-lrc p.aplayer-lrc-current {
        
        display: none;
        
        font-size: 15px;
        color: #42b983;
    }

    
    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body {
        left: -66px !important;
    }

    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body:hover {
        left: 0px !important;
    }

    
</style>
<div class="">
    
    <div class="row">
        <meting-js class="col l8 offset-l2 m10 offset-m1 s12"
                   server="netease"
                   type="playlist"
                   id="503838841"
                   fixed='true'
                   autoplay='false'
                   theme='#42b983'
                   loop='all'
                   order='random'
                   preload='auto'
                   volume='0.7'
                   list-folded='true'
        >
        </meting-js>
    </div>
</div>

<script src="/dai_modest/libs/aplayer/APlayer.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/meting@2/dist/Meting.min.js"></script>

    

    <div class="container row center-align"
         style="margin-bottom: 0px !important;">
        <div class="col s12 m8 l8 copy-right">
            Copyright&nbsp;&copy;
            
                <span id="year">2019-2023</span>
            
            <span id="year">2019</span>
            <a href="/dai_modest/about" target="_blank">戴某人</a>
            |&nbsp;Powered by&nbsp;<a href="https://hexo.io/" target="_blank">Hexo</a>
            |&nbsp;Theme&nbsp;<a href="https://github.com/blinkfox/hexo-theme-matery" target="_blank">Matery</a>
            <br>
            
                &nbsp;<i class="fas fa-chart-area"></i>&nbsp;站点总字数:&nbsp;<span
                        class="white-color">128.1k</span>
            
            
            
                
            
            
                <span id="busuanzi_container_site_pv">
                &nbsp;|&nbsp;<i class="far fa-eye"></i>&nbsp;总访问量:&nbsp;
                    <span id="busuanzi_value_site_pv" class="white-color"></span>
            </span>
            
            
                <span id="busuanzi_container_site_uv">
                &nbsp;|&nbsp;<i class="fas fa-users"></i>&nbsp;总访问人数:&nbsp;
                    <span id="busuanzi_value_site_uv" class="white-color"></span>
            </span>
            
            <br>

            <!-- 运行天数提醒. -->
            
            <br>
            
        </div>
        <div class="col s12 m4 l4 social-link social-statis">


    <a href="mailto:861796830@qq.com" class="tooltipped" target="_blank" data-tooltip="邮件联系我" data-position="top" data-delay="50">
        <i class="fas fa-envelope-open"></i>
    </a>







    <a href="tencent://AddContact/?fromId=50&fromSubId=1&subcmd=all&uin=861796830" class="tooltipped" target="_blank" data-tooltip="QQ联系我: 861796830" data-position="top" data-delay="50">
        <i class="fab fa-qq"></i>
    </a>







    <a href="/dai_modest/atom.xml" class="tooltipped" target="_blank" data-tooltip="RSS 订阅" data-position="top" data-delay="50">
        <i class="fas fa-rss"></i>
    </a>

</div>
    </div>
</footer>

<div class="progress-bar"></div>


    <!-- 搜索遮罩框 -->
<div id="searchModal" class="modal">
    <div class="modal-content">
        <div class="search-header">
            <span class="title"><i class="fas fa-search"></i>&nbsp;&nbsp;搜索</span>
            <input type="search" id="searchInput" name="s" placeholder="请输入搜索的关键字"
                   class="search-input">
        </div>
        <div id="searchResult"></div>
    </div>
</div>

<script type="text/javascript">
$(function () {
    var searchFunc = function (path, search_id, content_id) {
        'use strict';
        $.ajax({
            url: path,
            dataType: "xml",
            success: function (xmlResponse) {
                // get the contents from search data
                var datas = $("entry", xmlResponse).map(function () {
                    return {
                        title: $("title", this).text(),
                        content: $("content", this).text(),
                        url: $("url", this).text()
                    };
                }).get();
                var $input = document.getElementById(search_id);
                var $resultContent = document.getElementById(content_id);
                $input.addEventListener('input', function () {
                    var str = '<ul class=\"search-result-list\">';
                    var keywords = this.value.trim().toLowerCase().split(/[\s\-]+/);
                    $resultContent.innerHTML = "";
                    if (this.value.trim().length <= 0) {
                        return;
                    }
                    // perform local searching
                    datas.forEach(function (data) {
                        var isMatch = true;
                        var data_title = data.title.trim().toLowerCase();
                        var data_content = data.content.trim().replace(/<[^>]+>/g, "").toLowerCase();
                        var data_url = data.url;
                        data_url = data_url.indexOf('/') === 0 ? data.url : '/' + data_url;
                        var index_title = -1;
                        var index_content = -1;
                        var first_occur = -1;
                        // only match artiles with not empty titles and contents
                        if (data_title !== '' && data_content !== '') {
                            keywords.forEach(function (keyword, i) {
                                index_title = data_title.indexOf(keyword);
                                index_content = data_content.indexOf(keyword);
                                if (index_title < 0 && index_content < 0) {
                                    isMatch = false;
                                } else {
                                    if (index_content < 0) {
                                        index_content = 0;
                                    }
                                    if (i === 0) {
                                        first_occur = index_content;
                                    }
                                }
                            });
                        }
                        // show search results
                        if (isMatch) {
                            str += "<li><a href='" + data_url + "' class='search-result-title'>" + data_title + "</a>";
                            var content = data.content.trim().replace(/<[^>]+>/g, "");
                            if (first_occur >= 0) {
                                // cut out 100 characters
                                var start = first_occur - 20;
                                var end = first_occur + 80;
                                if (start < 0) {
                                    start = 0;
                                }
                                if (start === 0) {
                                    end = 100;
                                }
                                if (end > content.length) {
                                    end = content.length;
                                }
                                var match_content = content.substr(start, end);
                                // highlight all keywords
                                keywords.forEach(function (keyword) {
                                    var regS = new RegExp(keyword, "gi");
                                    match_content = match_content.replace(regS, "<em class=\"search-keyword\">" + keyword + "</em>");
                                });

                                str += "<p class=\"search-result\">" + match_content + "...</p>"
                            }
                            str += "</li>";
                        }
                    });
                    str += "</ul>";
                    $resultContent.innerHTML = str;
                });
            }
        });
    };

    searchFunc('/dai_modest/search.xml', 'searchInput', 'searchResult');
});
</script>

    <!-- 回到顶部按钮 -->
<div id="backTop" class="top-scroll">
    <a class="btn-floating btn-large waves-effect waves-light" href="#!">
        <i class="fas fa-arrow-up"></i>
    </a>
</div>


    <script src="/dai_modest/libs/materialize/materialize.min.js"></script>
    <script src="/dai_modest/libs/masonry/masonry.pkgd.min.js"></script>
    <script src="/dai_modest/libs/aos/aos.js"></script>
    <script src="/dai_modest/libs/scrollprogress/scrollProgress.min.js"></script>
    <script src="/dai_modest/libs/lightGallery/js/lightgallery-all.min.js"></script>
    <script src="/dai_modest/js/matery.js"></script>

    <!-- Baidu Analytics -->

    <!-- Baidu Push -->

<script>
    (function () {
        var bp = document.createElement('script');
        var curProtocol = window.location.protocol.split(':')[0];
        if (curProtocol === 'https') {
            bp.src = 'https://zz.bdstatic.com/linksubmit/push.js';
        } else {
            bp.src = 'http://push.zhanzhang.baidu.com/push.js';
        }
        var s = document.getElementsByTagName("script")[0];
        s.parentNode.insertBefore(bp, s);
    })();
</script>

    
    <script src="/dai_modest/libs/others/clicklove.js" async="async"></script>
    
    
    <script async src="/dai_modest/libs/others/busuanzi.pure.mini.js"></script>
    

    

    

    <!--腾讯兔小巢-->
    
        <div style="position:fixed;bottom:125px;right:16px;cursor: pointer;">
            <a title="兔小巢" target="_blank" rel="noopener" href="https://support.qq.com/products/"><i class="fa fa-comments fa-3x"  aria-hidden="true"></i></a>
        </div>
    
    
    <script type="text/javascript" color="0,0,255"
        pointColor="0,0,255" opacity='0.7'
        zIndex="-1" count="99"
        src="/dai_modest/libs/background/canvas-nest.js"></script>
    

    
    
    <script type="text/javascript" size="150" alpha='0.6'
        zIndex="-1" src="/dai_modest/libs/background/ribbon.min.js" async="async"></script>
    

    
    <script type="text/javascript" src="/dai_modest/libs/background/ribbon-dynamic.js" async="async"></script>
    

    
    <script src="/dai_modest/libs/instantpage/instantpage.js" type="module"></script>
    

<script src="/dai_modest/live2dw/lib/L2Dwidget.min.js?094cbace49a39548bed64abff5988b05"></script><script>L2Dwidget.init({"log":false,"pluginJsPath":"lib/","pluginModelPath":"assets/","pluginRootPath":"live2dw/","tagMode":false});</script></body>

</html>
